Don't hide all overlays when leaving dream scene if the device is locked.

This fixes dreaming -> bouncer transition on flexiglass.

Bug: 432335857
Test: verified manually
 1. Enroll SFPS
 2. Enable screen saver
 3. Go to screen saver
 4. Auth using SFPS 5 times incorrectly
 5. Dreaming should transition to bouncer without any issues.
Flag: com.android.systemui.scene_container
Change-Id: I10cb8b465aeb54dc886619a708ce02d636688706